This invention relates to curable compositions comprising polymers containing silyl groups.
Compositions of organic polymers containing silyl groups which are capable of being cured to rubber-like materials upon exposure to moisture in the atmosphere may be used, for example, as sealants for buildings and the like. Compositions based on polysulfides, urethanes and silicones have been commercially available as elastomeric sealants but each has its own set of problems and leave something to be desired. The polysulfide based compositions have poor resistance to heat, that is, they lose elasticity, and have poor set resistance. This latter property may be defined as the amount (percent) by which a standard test piece fails to recover its original thickness after being subjected to a standard compressive or extensive load for a fixed period of time. A higher recovery percentage means good set resistance. The urethane based compositions have poor resistance to heat and poor resistance to weather. Insofar as the silicone based composition is concerned, it exhibits good set resistance, but suffers from such problems as inadequate curing under hot and humid conditions and bad staining to stone.
Curable compositions having good storage stability and adhesion, as well as excellent strength and estensibility, were disclosed in Japanese Laid Open Pat. No. 73998/1977. However, their set resistance was not fully satisfactory. Thus, there is still a deficiency in the art of a curable composition which has good physical properties and in addition good set resistance.